I had a bad experience with Dell when i blew the power supply of my sisters machine up. The conversation was something like this:
Dell: What's the nature of the problem?
Me: the power supply has gone, i need to order a new power supply.
Dell: Ok sir, we'll try and identify the problem.
Me: I know what the problem is, its the power supply, i need to order a new one.
Dell: What happens when you press the power button?
Me: Nothing, because the power supply is broken. None of the diagnostic LEDs light up either- because the power supply is broken.
Dell: What colour is the LED on the power button of the monitor?
Me: It's in standby mode because the computer is not on (because the power supply is broken!)
Dell: Can you open the computer up and tell me if there are any lights on the motherboard?
Me: No, because the power supply is broken.
Dell: What about if you hold the power button down?
Me: Nope, still not worky, power supply still dead.
Dell: Ok sir, it appears that the power supply in your machine is broken, we can sort you out with another one.
Then i got put through to another department, who, surprise surprise couldn't help because they weren't the correct department. Got put through to another department who told me that because the machine is now out of the Dell product range, they don't supply the parts anymore, and i'd have to order through the 3rd party supplier.
They gave me a number, which was wrong so I had to go online to get the correct one. By this time I was so fed up with it all (30mins on't phone), that I couldn't face calling the 3rd party company, but got a whinging from my dad, so I had to call them. The conversation was something like:
Them: Good afternoon, how can I help?
Me: I'd like to order a replacement power supply for my Dell #modelnumber# please.
Them: Ok sir, that's £not_that_much, would you like anything else?
So angry!! How can Dell be such a pain in the arse, yet I was off the phone to the other company in less than two mins?!
Conclusion: Dell are rubbish :p